1. Field of the Invention
The present invention relates to an optical recording medium which comprises a photopolymerizable monomer and to an optical recording process using such a medium.
2. Description of the Prior Art
There have so far been known optical recording media which comprise films as recording layers formed from organic compounds; for example, such media are disclosed in Japanese patent application Laid-Open Nos. 16,948/81 and 125,246/83. Both of the disclosures relate to a recording media having a recording layer composed of an organic coloring matter for recording and reproducing information by use of laser beams.
The medium disclosed in the latter patent application laid-open gazette employs a recording layer formed from cyanine coloring matter represented by the general formula ##STR1## The recording layer is formed by applying a solution of the coloring matter in the thickness of up to 1000 .ANG., for example, about 300 .ANG., on a plastic substrate using a spinner coater or the like. When the molecular distribution or orientation in the layer is random, the incident light scatters in the layer and the extent of chemical reaction caused by light irradiation varies microscopically at every irradiation. In consequence, for recording media, the molecular distribution and orientation in the layer is desired to be uniform and the layer thickness is required to be minimized for the purpose of obtaining high-density recording. By coating methods, however, the lower limit of the layer thickness is about 300 .ANG. and the random molecular distribution and orientation are inevitable.
Meanwhile, Japanese patent application Laid-Open Nos. 42,229/81 and 43,220/81 disclose that a built-up film of a diacetylene compound formerly proposed as one of resist materials that shows a high light quantum yield and has a superior resolution can also be applied to thin film electrooptic devices, electro-acoustic devices, and piezoelectric and pyroelectric devices, etc.
Recently an improved process for producing built-up films of diacetylene compounds is disclosed in Japanese patent application Laid-Open No. 111,029/83. Built-up films of diacetylene compounds produced according to these inventions are used for film-optic devices and integrated circuit elements, after the polymerization thereof by ultraviolet irradiation to form a polymer film or partial polymerization thereof by ultraviolet irradiation under masking and pattern formation by removing the unpolymerized portions.
However, these patent applications are all limited to diacetylene compounds and do not describe the possibility of erasing information once recorded when built-up films of a diacetylene compound are used for film-optic devices.